(1) Field of the Invention
The invention relates to a method of toxic gas removal in the fabrication of integrated circuits, and more particularly, to a method removing residual toxic gas in a sidewall polymer by non-reactive ion sputtering in the manufacture of integrated circuits.
(2) Description of the Prior Art
As device geometry shrinks, the total sidewall area on the wafer becomes larger and larger. That means that more and more polymer etch byproducts may accumulate on the sidewalls of semiconductor device features. This may cause a safety issue in some polymerizing processes, for example silicon shallow trench etching. Some of the toxic gas species used in the etching process may be trapped or adsorbed in the processing-induced polymer and then released into the atmosphere at a later point in fabrication thereby raising safety issues. The conventional practice is to leave the wafer in the chamber for a much longer period of time following etching to pump away the toxic residual gas reactant/species. However, this extra chamber time sacrifices throughput.
U.S. Pat. No. 6,177,331 to Koga teaches a reactive ion etch physical sputtering process using Argon to etch away corner portions of the hard mask. U.S. Pat. No. 6,177,347 to Liu et al shows an Ar sputter method of removing a polymer within an opening. U.S. Pat. No. 4,931,409 to Nakajima et al removes a polymer using a NH4F aqueous solution. U.S. Pat. No. 5,514,247 to Shan et al removes metal flakes trapped in a polymer by adding a metal scavenging, halogen-bearing gas to the via etch process. U.S. Pat. No. 5,776,817 to Liang discloses a plasma etch and physical vapor deposition step. U.S. Pat. No. 5,846,884 to Naeem et al uses an RIE having a high-sputter component to reduce polymer buildup. U.S. Pat. No. 6,071,822 to Donohue et al removes a polymer using a fluorinated gas and an inert gas such as Ar. U.S. Pat. No. 5,759,921 to Rostoker shows a plasma etching process.
A principal object of the present invention is to provide an effective and very manufacturable method of removing residual toxic gases trapped by a polymerizing process after etching in the fabrication of integrated circuit devices.
Another object of the invention is to provide a method to remove residual toxic gases trapped by a polymerizing process by an inert ion sputter.
Yet another object of the invention is to provide a method to remove residual toxic gases trapped by a polymerizing process by an in-situ inert ion sputter.
In accordance with the objects of this invention a new method to remove residual toxic gases trapped by a polymerizing process by an inert ion sputter is achieved. A masking layer is, formed overlying a semiconductor substrate. An opening is etched through the masking layer into the semiconductor substrate whereby a polymer forms on sidewalls of the opening and whereby residual toxic gas reactants from gases used in the etching step are adsorbed by the polymer. Thereafter, the polymer is sputtered with non-reactive ions whereby the residual toxic gas reactants are desorbed from the polymer to complete removal of residual toxic gas reactants in the fabrication of an integrated circuit device.